The present invention relates to an aircraft fuselage comprising an outer insulation.
FIG. 1 schematically shows part of the fuselage 10 of an aircraft.
The fuselage 10 comprises a skin 12, which forms a barrier between the interior I and the exterior E of the fuselage. This skin 12 comprises an outer surface 14 in contact with the exterior E and an inner surface 16 in contact with the interior I. An outer coating in the form of at least one film of paint is applied to the outer surface of the skin in order to protect said skin against corrosion, to beautify said skin and to improve the aerodynamic characteristics of the aircraft.
During the flight phase, an air-conditioning system makes it possible to maintain the temperature in the interior I of the fuselage around 20° C., whereas the temperature at the exterior E of the fuselage is around −50° C.
In order to limit losses and to ensure passenger comfort, at least one insulation blanket 18 is provided, in the interior I of the fuselage, in the vicinity of the inner surface 16 of the skin of the fuselage.
Once this insulation blanket 18 has been placed in position, a space remains between said insulation blanket 18 and the skin 12, and the hot and humid air coming from the interior I of the fuselage circulates in said space.
During the flight, the inner surface 16 of the skin is at a temperature below 0° C., such that the humidity coming from the interior I of the fuselage tends to condense and to freeze at said inner surface 16. This phenomenon contributes to drying out the air in the interior I of the fuselage and causes discomfort for the passengers.
During the phase of descent, the temperature of the air outside the aircraft becomes increasingly warmer, such that the ice formed on the inner surface 16 tends to melt and to trickle onto the insulation blanket 18 until it reaches the lower part of the fuselage, where the condensates are collected and then discharged.
Consequently, in addition to the insulating function thereof, the insulation blanket 18 serves to seal the interior I of the fuselage and to drain the condensates so as to prevent these from trickling into the interior I of the fuselage, in particular onto sensitive systems, such as electrical circuits.
In order to ensure these two functions, an insulation blanket 18 in accordance with one embodiment is formed by a layer of thermally insulating material, such as glass wool, encased in a tight film made of plastics material.
In addition to the skin 12, the fuselage comprises a structure 20 that supports the skin 12 and that comprises numerous elements 22 extending toward the interior I of the fuselage by passing through the insulation blanket 18. Each traversing element 22 constitutes a thermal bridge and requires the design of complex forms of the insulation blanket 18 and/or alters the insulation performances.
In accordance with another aspect, the insulation blankets 18 are installed immediately after the structural assembly of the aircraft, such that they can withstand degradations during the installation of other systems and equipment of the aircraft. The replacement of damaged insulation blankets 18 requires the disassembly of a number of parts, which may be fragile, such as pipework.
Lastly, the insulation blankets 18 must be made of specific materials that meet the requirements of the FST (fire smoke toxicity) standards relating to toxic fumes in the case of fire.
The present invention also aims to overcome the disadvantages of the prior art.